Porphyrin-based metal–organic frameworks: Advanced materials for the oxygen evolution reaction

The design and synthesis of metal-organic frameworks (MOFs)-based electrocatalysts for water-splitting oxygen evolution reaction (OER) have attracted significant interest due to their exceptional surface area, tunable porosity, and distinctive characteristics. However, developing highly durable, stable, and efficient electrocatalysts capable of delivering high current densities at low overpotentials remains a formidable challenge for the OER. Herin, we successfully synthesized a series of new heterometallic porphyrin-based MOFs using Cerium (Ce) and Cobalt (Co) as metal nodes coordinated with 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP) as organic ligands hereafter, namely TCPP(Co)-MOF, TCPP(Ce)-MOF, and TCPP(Ce)Co-MOF. All these MOFs were tested as electrode materials for electrochemical water splitting. The synthesized electrocatalysts were analyzed using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, and energy-dispersive spectroscopy (EDS) mapping to investigate their structural features, morphology, and elemental composition. The heterometallic MOF-based electrocatalyst, TCPP(Ce)Co-MOF, demonstrated exceptional performance for OER in a 1M KOH electrolyte, achieving an overpotential of 156 mV @10 mA cm⁻², a Tafel slope of 46 mV dec⁻¹, and a high current density of 596 mA cm⁻² within a narrow potential range. The electrocatalyst exhibited remarkable chrono-potentiometric stability at 10 and 50 mA cm⁻² current density for 50 hours of testing in an alkaline environment. Hence, the developed nickel foam-supported TCPP-derived heterometallic MOFs could be considered a promising electrocatalyst for boosting the OER in fuel cell applications.